The invention relates to an ultrasonic measuring arrangement for the flow, speed of sound, density, viscosity, and/or temperature measurement of flowing media, comprising a measurement tube having a measurement section, said tube being disposed in an area of the measurement housing, wherein the ultrasonic measuring arrangement comprises at least two ultrasound transceivers disposed at a distance as sensors for sound transmission through the measurement section in the direction of flow of a medium and opposite thereto, and for signal recording. Additionally the invention relates to a method for producing such an ultrasonic measuring arrangement.
In order to establish a measuring section for good sound transmission during the use of ultrasonic measuring arrangements, particularly in the field of flow rate measurements of flowing media, various concepts are known to embody measurement sections inside housings. For small nominal diameters in the range of up to approximately 25 mm, from EP 0 088 235 and EP 0 681 162 a U-shape is known, and alternatively a Z-form or a double-Z form are also known, and depending on the space available and the application additional, basically arbitrary, complicated forms of measurement sections can be used.
All measurement sections known exhibit the disadvantage that, for reasons of production technology, their profile required for the measurement process requires a multi-part component and the respective parts must subsequently be connected by way of welding creating seams or seals. This circumstance in turn is disadvantageous in that the respective seals may become leaky and develop capillaries between the housing and the seal. On the other hand, welding spots may show pores, inclusions, or other irregularities. The transported medium to be measured can adhere to these weak spots, which particularly in the food industry can lead to problems with regards to hygiene. Here, another problem can occur in the chemical industry, if residual media remains, which e.g., may endanger the personnel during disassembly of the device.
Within the above-mentioned small nominal diameters there are other systems known, for example, from DE 101 20 355, DE 39 11 408, DE 39 41 546, and WO 2007/065557, which operate by way of reflection or even multiple reflections. However, each reflection removes a portion of the irradiated sound energy, so that here strong signal transmissions are required, which in turn may lead to problems with respect to electromagnetic tolerances, or the signal received weakens to such an extent that it becomes hard to distinguish it from the permanent background noise and thus the measurement collection requires additional expenses.
From DE 101 09 161 a measuring arrangement is known, in which inside a device having a large nominal diameter, a smaller diameter is quasi simulated by a nozzle in a measuring tube, by way of the nozzle concentrating the flow to a small area. However, such arrangements have a fixed, predetermined direction of flow and cannot measure any backflow.
Finally, U.S. Pat. No. 5,716,038 discloses a measuring arrangement having sensors that are contacted by the media, which arrangement is complicated in its production and potentially susceptible to sealing problems. EP-A-1 413 858 discloses a measuring arrangement, in which the measurement essentially occurs cross-wise in reference to the direction of flow. WO 94/20822 discloses a measuring arrangement, in which sensors must be subsequently introduced into recesses, provided for said purpose at the measurement tube, and which subsequently must be closed and sealed.